Reconstruction refers to obtaining a continuous time signal from the samples of a signal. We do this by passing $y[n]$ (the sampled signal) into a low pass filter and that would result in a reconstructed signal $y(t)$ (infinite sum of sampled signals times shifted sinc functions, known as bandlimited interpolation) ### The Zero-Order Hold - Need? - Cannot analyze infinite sums of sinusoids at values of $t$ that are not equal to $nt$ - Cannot physically realize ideal low pass filter - So, what do we do? - Constant voltage of value $y[n]$ is held for $T$ seconds - Results in a wave form that has stairstep characteristic to it